Lighting apparatus



Dec. 13, 1927.

L. x. CHAMPEAU LIGHTING APPARATUS Filed June l 1.924

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ATTORNEYS @so EE@ 1927 L., X. CHAMPEAU LIGHTING APPARATUS Filed. June 177 192A 5 She'bs-Sheet 3 7 v l Y 54g 7 v r |l|' V v M H u n Inh u! I M w N' 1|" l W .11 'mi E INVENTOR www@ Patented Dec. 134, 1927.

umriss STAT-Es PATENTl ormoni LAWRENCE X. GHAMPEAU, or NRW YORK, N. Y., AssIeNoR, BY MnsNn AssIeNMENTs, To .RIRBY INCORPORATED, A CORPORATION or NRW YORK.

LIGHTING APPARATUS. y

Application led June 17, 1924. Serial 1l'o.,'?20,4.93.`

This invention relates to lighting appa rat-us for galleries, school rooms, exhibition halls, museums, and certain types of factories, shops, and work or other rooms in which it may be desirable to distribute the Y, light according to a predetermined plan.

The principal object of my invention is yto direct daylight into interiors to produce a maximum illumination and even distributionv of the light admitted over the desired portions of'the interior, while maintaining `a relative darkness in other portions where this condition may be advantageous.

One embodiment of the invention has been illustrated in the accompanying draw-` ings, in which` Fig. 1 is a vertical sectional view through a room, showing the device in use;

Fig. 2 is a plan view of one of the refracting units making up the ceiling;

Fig. 3 is a transverse section at right'angles to the axes of theprismatic portions of such a refracting unit on a greatly enlarged scale;

Fig. 4 is an elevation of such a` unit as seen from the right of Fig.. 3;

Fig. 5 is a perspective view taken diagonally of the room, as viewed from a point between the ceiling and one form of light 3o deflecting structure;

' Fig. 6 is a cross `section on an enlarged scale through a combined light intercepting and retracting unit, taken on line 6-6 of Fig. 8; I

Fig. 7 is a transverse view through the vupper part of a room employing the light controlling apparatus shown in Fig. 6; and` Fig.y 8 is a plan view of part of a ceiling of the t-ype shown in ig. 7

In art galleries the paintings to be viewed are hung along the walls at some distance above the floor, and should be more or less evenly illuminated over their entire surfaces. For eflicient use of the available space, the fportions of the walls near the corners of the gallery should be as brightly lighted as the central portions in order that pictures hung at any point may be viewed to equal advantage., Again it is desirable that paintings should be hung Abehind protectingglass, but prior to this invention. it has not been customary so to protect pictures on exhibit-ion, because the view of observers has been so marred by reflections seen in the cover glass as to prevent proper appreciation of the paintings themselves. j

This invention solves these problems of art gallery lighting, first, by admitting light through a skylight past a suitable intercepter to a refractingv ceiling which ,directs the incident light rays toward the walls, leaving the central space directly beneath the ceiling relatively dark. Thus an observer standing at the usual distance from a paintinghung on the wall, always has his back ,toward the source of light andthe whole front of his vbody is in the shadow, so that he can see his reflection in the cover glass on the pictures but dimly, if at all. The retract-ing ceiling also directs sufficient light into the corners of'the room, that pictures hung on any part of the wall appear to equal advantage.

In school rooms, library reading rooms, work shops for the lneedle trades, and various 4machine shops in which the operatives face constantly in the same direction, it is desirable that light shouldall come from above and to the rear ot' the persons in the room,

so as to pass diagonally over their left shoulders upon their work. This desirable result may be easily attained by one form of the present invention, in whichthe refracting ceiling is made up of transparent material, such as glass having a multiplicity of parallel prisms extending diagonally across the room.

In the northern hemisphere the sun', at places in latitudes greater than 231/2", always crosses the meridian south of the zenith, so that if its rays were directly admitted to the room to be illuminated, the north wall would receive more light than the south wall. In order to obtain uniform distribution of the light which strikes the rerac'ting 95 ceiling of this invention, any usual light intercepting structure may be interposed between the transpartent roof and the ceiling of the room to be illuminated. Wherethe very best results are desired and the expense of installation is a secondary consideration, the light deflecting'structure is preferably of the type shown in applicants Patent, No.` 1,419,918, and' which has been illustrated in Figs. 1 and 5 of the present application. In these figures, 9 9 designates the easterly and westerly wallsl of the room to be illuminated, while the north or south wall is indicated at 10. All the light is admitted through a transparent roof 11, which, in the case of art galleries, may be of considerably smaller area thanthat of the floor 12. Between the ceiling 13, which is formed of transparent refracting material to be described, and the roof is an intercepter which vconsists of a series 4of suitably spaced deiecting members 14 which extend in a general eastand West direction, and are mounted for rotation on horizontal axes. Between adjacent members 14 and supported for movementon vertical axes, as described in applicants patent above referred to, are additional reflecting members 15, the position of which may be varied in accordance with the position of the sun to prevent directy rays of the sun from striking the ceiling 13. By properly operating the deliectorspdescribed, the course ofrays of light passing through the roof 11 may be altered so that by far the greater portion of the light will pass more or less vertically ldownwards from the deflectors to the upper surface of the ceillng.

The arrangement of the prisms in the ceiling differs according tothe particular lighting requirements of the room to be lighted. In the case of an art gallery where pictures are hung on the fourwalls, the ceiling is divided up into four sections of approximately equal area, designated in Fig. 5 as N. E., N. W., etc. according to the points of the compass. Each section of the ceiling consists of one or more refracting plates 16 arranged to bend thev nearly vertical rays incident -on its upper surface away from the center of the room. For convenience in installation and economy of manufacture, each section of the ceiling is made up of a suilicient number of rectangular plates supported on mullions 17 running in one direction.

intersected by transverse mullions 18. Each plate preferably has a plane lower surface, while its upper surface is sub-divided into a plurality of prisms 19 having' parallel axes. The particular angle of the prisms is governed by the optical qualities of the glass, or other transparent material of which theyare composed, and by the dimensions of the room to be lighted. Thus in the gallery shown in Fig. 1, the prism plates'are designed to refract a vertical .ray of light to an angle of apprpximately 415 with the vertical. By arranging the axes of the prisms l in each section of the ceiling parallel to each other and at such an angle to the side walls that a line at right angles to the axes lthe prismatic ceiling Aat other angles than 900 is, of course, retracted somewhat differ- -ently so that not all the light goes into the corners, but by a little experimentation in positioning the defiectors, it will be found that the central parts of the Walls being nearer the center of the ceiling than the corners receive more of these nonvertical 'rays of light and maybe illuminated to Very approximately the same degree as the corners.

By a consideration of the foregoing in connection with the illustration in Fig. 1, it will be seen that a great deal 'more light is directed toward the walls than leaks straight downv through the ceiling, so .that the floor of the gallery is relatively dark and observers standing a little removed from the walls, as .they must be to see the subjects u hung for exhibition, are so dimly lighted as to cause little or no reflection in the cover glasses of the exhibits. ,A

To produce still more even distribution of the light than can be obtained by the use of prisms having plane faces, it is desirable that the more nearly horizontal surfaces of the prisms should be irregularly curved, as illustrated in Figs. 3 and Al. Thus the rays incident on the one surface of the prism in a vertical plane, as shown at 20, are not refracted into a plane but into a wavy surface in which the most deflected rays follow the path 21 shown in full lines, while the least deflected follow the dotted path 22, and the other `rays are deiected between these limits. The use of such irregular prismatic glass in the ceiling entirely does away with any shadow which the light deiiecting structure might otherwise appear to cast, and so breaks up light passing through the ceiling that an observer standing on the floor cannot see distinctly any object above the ceiling. Moreover, the use of such irregular prism plates enables satisfactory results to be obtained in many instances by the aid of much simpler liglit deiiecting structures than that above described.

In Figs. 6, 7 and 8 I have shown such a simplified light deflecting stucture in which the deflectors are closely adjacent the upper face of the prism plates. struction each prism plate supports a cellular light deiieetor preferably composed of thin metal sheets 23 in parallel spaced rela- In this eontion, which are intersected at rightgangles by similarly arranged sheets 24, each sheet being cut partly through at its .intersections l with cross sheets, so that the defiector as a whole resembles an egg-crate. The sheets are preferably painted white or otherwise treated to make them good lightl reflectors. The deflector and prism plate are housed in a dust-proof b'ox having vertical side walls 25, three of which have integral upper flanges 26 and lower flanges 27 adapted to grip the edges of cover plate 28 and prism plate 16, respectively. These plates slide into place in the box and may be removably secured by separate upper` and lower flanges 29, 30 fastened on the fourth side of the box as by screws 31.l The cover plate 28 is a thin sheet of plane surfaced transparent glass 28, which with its surrounding flanges serves to excludeI dust from the light deflector and the upper `face of the prism plate, thereby greatly decreasing the difiiculty and expense of keeping these surfaces clean.

The light deflecting boxes may be made up in standard sized units ready for installation upon supporting mullions, which preferably consistof inverted T rails, as shown at 32. In case of damage to any part of ysuch a box, it may be readily lifted out and place where the lighting apparatus is in-j stalled and the particular requirements of any given installation. For example, in latitude 40'the sun at the summer solstice has a zenith distance of only llo, so that if it `is required that no direct rays of the sun strike the prism plate, the depth of the deiiecting sheets must be nearly 31/2 times as great-as their horizontal distance apart. As this proportion would in some cases admit too little light during the-winter season, it has been found desirable to make the sheets about twice as deep vertically as` their horizontal separation, and to provide a series of east to west extending shutters 14 above the defiecting refracting structure,as shown in Fig. 7

However, for many uses such as in work shops, school rooms, and other places where' people sit facing more or less continuously in the same direction, a little direct sunlight striking the prism plates for a short time each day during the weeks near the summer solstice, is vnot seriously harmful, and the shutters ma be dispensed with. For installations w iere it is desired to haveall the light rays in the room directed ap roximately in the same direction, as over t e left shoulders of the people in the room, the ceiling consists of a single section in which the axes of all the prism plates are parallel to While the irregularly wavy surfaced prisms shown in Figs. 3 and 4 break up the',

light very satisfactorily so as to give a welldistributed illumination below, good results may in -many cases be obtained by the use of plates having plane surfaced prisms. The invention is not limited to any specific d-e- 'fleeting or refracting means, but is believed to include all suitable combinations of delecting and refracting means to control light admitted through a skylight to a place to be illuminated. While only a few of the many varieties of rooms which can be lighted advantageously by the use of this invention have been enumerated, it is believed that better results can be obtained in lighting the top Hoor of almost any building with this.

invention than could be obtained through the use of windows in the-vertical walls.

Vhat I claim is: i l. In a lighting apparatusa'room to be lighted, an approximately rectangular prismatic ceiling divided into four sections by intersecting lines from' the centers of opposite room walls, the apices of the prisms being up and the axes of the prisms in each section being diagonal, the angles of the prisms being so chosen as to direct light falling substantially vertically thereon into the corners of the room to be lighted, and means for controlling the light falling on the up-` per surface of the ceiling.

y 2. In a lighting apparatus in combination, a skylight, cellular light-deflecting members below the skylight and having deiiecting sides arranged to deflect light coming from llfl an angle into a substantially vertical .downward direction, a prismatic ceiling beneath said deflecting members consisting in prisms with vtheir yapices up and having their axes and angles'so chosen as to refract the lfight impinging thereon into definite predetermined directions in the room.

3. An apparatus according to claim 2 in wkhich the deflecting members are adjusta le.

4. In a lighting apparatus, a skylight, ap

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in a definite predetermined direction in the room.

5. An apparatus aceordingto claim 4 in which the top of the ceiling formed by the prismatie plate and cellular light dcflectors is covered with a transparent plate to form a dust-tight box.

6. In lighting apparatus, a box having a plurality of Vertical sides, flanges at the bottom edges of the sides to receive and hold 10 'a refracting plate, and Vertical light reflect- LAWRENCE X. CHAMPEAU. 

